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HEPATITIS A, B, C, D, E, G: AN UPDATE
Acute and chronic liver diseases are an
assortment of disorders brought to the clinician’s attention by abnormal liver function
tests or specific signs and symptoms. The
differential diagnosis includes disorders that
have primary or secondary liver involvement.
This paper will be limited to the epidemiology,
clinical manifestations, diagnosis, treatment,
and prevention of the different viral liver
diseases: A, B, C, D, E and G. (Ethn Dis.
2007;17[suppl 2]:S2-40–S2-45)
Key Words: Hepatitis A, Hepatitis B, Hepatitis C, Hepatitis D, Hepatitis E, Hepatitis G,
Interferon, Ribavirin
Gairy F. Hall, MD
INTRODUCTION
The word hepatitis connotes an
infection or inflammation of the hepatocytes, as evidenced by abnormal liver
function tests (LFTs). This, however, is
a nonspecific term since the laboratories
combine hepatic enzyme tests (aspartate
aminotransferase [AST], alanine aminotransferase [ALT]) and synthetic tests
(albumin, bilirubin, and prothrombin
time [PT]) into LFTs. These tests can
be elevated in a healthy individual.1,2
The differential diagnoses of hepatitis should include, at a minimum: virus
infection; drugs or alcohol abuse; hemochromatosis; thyroid, muscle, and
autoimmune disorders; celiac disease;
alpha-1 antitrypsin deficiency; Wilson’s
disease; masses; and fatty liver. This
article will be limited to the current
appraisal of the epidemiology, clinical
manifestations, diagnosis, and treatment
of the different viral hepatic disorders:
hepatitis A, B, C, D, E, and G.
HEPATITIS A
Epidemiology
From the University Health Department, Northeastern University, Boston, Massachusetts.
Address correspondence and reprint
requests to: Gairy Hall, MD, FACP, Northeastern University, University Health &
Counseling Service, 135 Forsyth Building,
Boston, MA 02115-5000, USA; 617-3735190; 617-373-4142 (fax); [email protected]
S2-40
Hepatitis A virus (HAV) was first
recognized in 1947, but it has been
around for centuries. The two distinct
forms of the virus were only identified
in 1973, consisting of a RNA virus with
four genotypes.3 It occurs worldwide
but is highly prevalent in the developing
countries and Greenland; however, the
global incidence is decreasing because of
improved sanitary and living conditions.
In the United States, the incidence of
hepatitis A has declined dramatically
with the institution of the hepatitis A
vaccine.
HAV is spread mainly by the fecaloral route in low-socioeconomic areas,
but person-to-person spread has occurred in daycare centers, as have
community epidemics from contamiEthnicity & Disease, Volume 17, Spring 2007
nated foods (Mexican green onions).4
Sexual intercourse, blood, and intravenous drugs are minor routes of transmission of this virus as opposed to the
other viral hepatitis disorders.
Clinical Manifestations
HAV infection is usually an acute,
self-limiting disease with no sequelae or
chronic disease state. Its manifestations
vary according to the age of the patient
at presentation. Children usually have
a silent or subclinical course as opposed
to adults, who present with a wide range
of symptoms, from an influenza-like
illness to fulminant hepatic failure.
Diagnosis
The diagnosis of HAV infection is
made by the presence of antibodies
against HAV in conjunction with the
clinical picture. The incubation period
is 30 days, with a range of 15 to
50 days. Hepatitis A virus (HAV)
immunoglobulin M (IgM) is the gold
standard for making the diagnosis;
however HAV IgG appears early and
remains positive for decades.
Treatment
Since HAV is usually a self-limiting
disease, treatment is generally supportive. Eighty-five percent of patients
recover by three months, and nearly
100% will recover by six months. Death
can occur in elderly patients or in those
concomitantly infected with hepatitis C
virus (HCV).
Prevention
Since HAV is predominately
spread by the fecal-oral route, the
mainstay of prevention is thorough
hand washing, heating foods properly,
and avoiding water and raw foods in
endemic areas. Household bleach
(1:100 dilution) will adequately inactivate the virus. Passive immunity
HEPATITIS UPDATE - Hall
with intramuscular serum immune
globulin—given within two weeks of
exposure—will also provide protection
against this virus.
Vaccinations
The current epidemic of hepatitis A
could be avoided though a worldwide
viral campaign. The vaccines are safe,
efficacious, and relatively inexpensive.
The live, attenuated vaccine is no longer
in use because of the superiority of the
inactivated vaccines. Therefore, the inactivated vaccines are the only Food and
Drug Administration (FDA)-approved
vaccines that are used in the United
States. The inactivated vaccine provides
almost a 100% seroconversion rate and
a higher antibody response than even
serum immune globulin.
HEPATITIS B
Epidemiology
Hepatitis B virus (HBV) is a global
problem, with .350 million carriers
worldwide and 1.25 million in the
United States. An estimated 100,000
acute infections occur every year in the
United States. The mortality is substantial; each year 5000 patients in the
United States and .1 million worldwide die. In high-prevalence areas, the
predominant mode of transmission is
perinatal, while in low-prevalence areas
it is by sexual transmission and intravenous drug use.5 Blood transfusions
are another source of spread of HBV,
which remains the number one transmitted blood-borne virus in the healthcare environment.6
Individuals with HBV are at risk of
developing chronic infection, cirrhosis,
hepatic decompensation, and hepatocellular carcinoma. After the acute infection, 3%–5% of adults and up to
95% of children fail to produce a sufficient immune response to clear the
infection,5 thus going on to chronic
hepatitis B.
Clinical Manifestations
The clinical manifestations encompass a wide spectrum in the acute as well
as the chronic state. The virus has an
incubation period of two to six weeks.
Up to 70% of the acute cases present as
a subclinical anicteric state, and the
remainder present with jaundice, nausea
and vomiting, fevers, right upper quadrant pain, and hepatomegaly or fulminant hepatic failure. Some of these can
also present with extra hepatic manifestations.
If the LFTs are still elevated after six
months, then the individual is considered to have a chronic HBV infection,
but most patients with chronic hepatitis
B are asymptomatic.
Diagnostic Markers
The diagnosis of HBV is based on
the clinical presentation (complete history and physical); serologic, virologic,
and biochemical markers; and occasionally histologic markers. Hepatitis B
surface antigen (HBsAg) is the first
serologic marker to appear after infection. Hepatitis B ‘‘e’’ antigen
(HBeAg) indicates active viral replication, which makes a patient highly
contagious. Hepatitis B core antibody
(HBcAb) appears next and implies an
acute or chronic state or early recovery
period. Hepatitis B surface antibody
(HBsAb) is the last to appear and
implies recovery, immunity, or the
post-vaccine state.
Hepatitis B virus (HBV) DNA is
a virologic marker that measures the
level of viral replication. In the past, this
was measured by nonamplified hybridization assays, which have been replaced
by the current target amplification
assays, such as polymerase chain reaction (PCR). Hepatitis B virus (HBV)
has eight genotypes (A–H) based on
DNA sequencing and geographic distribution. However, genotype testing is
not used in clinical practice because its
relevance remains uncertain and controversial.
Ethnicity & Disease, Volume 17, Spring 2007
Elevated LFTs are an indication of
necroinflammation and represent the
biochemical markers. An elevated PT,
in conjunction with a low albumin,
usually indicates a poor prognosis or
chronicity.
Histologic examination by liver biopsy is the most specific and accurate
indicator of liver disease. Most individuals do not need a biopsy for diagnosis
or prognosis. However, some individual
with normal LFTs, and elevated HBV
DNA levels have substantial fibrosis on
biopsy.7
Treatment of HBV
The goals of HBV treatment are to
1) prevent cirrhosis and its complications; 2) prevent hepatocellular carcinoma; 3) obtain undetectable HBV DNA
levels; 4) normalize LFTs; 5) eradicate
HBeAg; and 6) improve histology. The
dilemma is that the above aims are
difficult to achieve because no standard
treatment algorithms, guidelines, or
treatment endpoints exist and because,
patients usually present with conflicting
data. Treatment should be considered
for individuals who are HBsAg-positive
or DNA-positive by PCR.8 The care of
the patient with normal ALT adds
a further dilemma to the treatment
options. With or without treatment,
circulating HBsAg can disappear but
HBV DNA can be found by PCR in the
liver of many individuals.9,10 Regardless
of the treatment, many experts believe
that chronic HBV infection can be
controlled but not cured.
Agents used to treat HBV include
interferon, lamivudine, adefovir, entecavir, and telbivudine.11 Tenofovir is
approved to treat HIV and HBV coinfection only. The Asian-Pacific guidelines also include thymosin alpha, which
is not an FDA-approved drug.
Interferon was the first drug used to
treat HBV in most countries and has
antiviral, antiproliferative, and immunomodulatory effects; in addition, it can
achieve a durable response after a finite
course of treatment (24–52 weeks). In
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HEPATITIS UPDATE - Hall
general, elevated LFTs and low HBV
DNA are the best predictors of treatment response.12 Interferon therapy,
however, is costly, must be given by
injection, and has many side effects.
The nucleoside/nucleotide analogues are
more potent than interferon in suppressing the HBV DNA levels and can lead
to undetectable levels by PCR; however,
interferon has immunmoduatory effects
and is the only drug associated with
HBVsAg conversion.13,14
Interferon usually causes a flare in
the ALT level because of immunemediated lyses of the hepatocytes. This
response, coupled with a later normalization of LFTs and a decrease in
inflammation, heralds a good prognosis.
Polyethylene glycol (PEG) is attached to the interferon molecule to
decrease its rate of absorption and renal
and cellular clearance, which increases
its half-life. This characteristic has propelled PEG-interferon as the drug of
choice over standard interferon.14 PEGinterferon is safe in compensated but
not decompensated cirrhosis.
Lamivudine, a nucleoside analog,
was originally used to treat HIV disease.
For HBV, it is well tolerated, is given
orally (100 mg/day), is relatively inexpensive ($7/day), has minimal side
effects, and can be used in decompensated cirrhosis; however, it is associated
with a high rate of drug resistance.
Adefovir, a nucleotide analog of
adenosine, can be used in HBeAgpositive or HBeAg-negative patients
and with compensated or decompensated cirrhosis. Its route of administration is oral (10 mg/day) at a cost of
$15–$20/day. It has a low rate of drug
resistance, but its duration of therapy is
greater than one year, and the dose
needs to be adjusted in renal insuffiency. Adefovir can be added to
lamivudine in case of lamivudine resistance; therefore, most physicians prefer adefovir.15
Entecavir is a nucleoside analog that
is given orally at 0.51 mg/day that
suppresses HBV DNA levels to a greater
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extent than lamivudine and adefovir. It
is associated with a low rate of drug
resistance, and the duration of therapy is
greater than one year. Entecavir has few
side effects, but like lamivudine, it has
a black box warning as a potential cause
of lactic acidosis, hepatomegaly, and
steatosis.
Tenofovir is a nucleotide analog
similar to adefovir, but it is more
potent. It is effective against HIV and
HBV and should only be used in coinfection with both diseases.
Telbivudine is a nucleoside analogue
that was recently approved by the FDA.
It is administered orally (600 mg/day)
and might suppress HBV DNA levels
to a greater extent than the previous
medications.
HBV Prevention
There are more than 350 million
carriers worldwide with HBV and
almost one million deaths per year.
The greatest hope to prevent this disease
is through primary prevention: safe
sexual practices, intravenous drug avoidance, and vaccination to increase herd
immunity. The HBV vaccine is safe, is
relatively inexpensive, has a high seroconversion rate, and is given in three
doses intramuscularly.
HEPATITIS C
Epidemiology
Hepatitis C infection affects .170
million people worldwide and .4
million Americans, but most are asymptomatic and unaware of their disease.16
Most patients acquired HCV by injection drug use or through pre-1990
blood transfusions. In the 1980s,
230,000 new cases were diagnosed each
year in the United States, but now only
36,000 cases are diagnosed year because
of decreased injection drug use and
increased awareness. The risk of transmission between monogamous partners
is low but rises with multiple sexual
partners. Rare forms of percutaneous
Ethnicity & Disease, Volume 17, Spring 2007
transmissions are tattoos, body piercing,
and intranasal cocaine use.
HCV is a small RNA virus with six
genotypes and was first identified in
1989. Genotype 1 accounts for 70%–
75% of all HCV infections in the
United States. It is the most common
blood-borne infection in the United
States, and the highest prevalence is in
persons aged 30–49 years old. In this
age group, the highest prevalence occurs
in African Americans.17
Most acutely infected patients are
asymptomatic or have a subclinical infection without jaundice. Chronic HCV
infection develops in 60%–80% of
infected persons, probably secondary
to rapid mutations that cause a failure
in T-cell immune recognition. Hepatitis
C virus (HCV) is the number one cause
of chronic liver disease, cirrhosis, and
liver transplantation in the United
States.
Diagnostic Tests
Hepatitis C virus (HCV) DNA in
the serum or liver is the first sign of
infection. The virus becomes positive in
tests days to weeks after exposure. This
test detects, quantifies, and characterizes
the viral particle components. This test
is further broken down into a qualitative
and a quantitative test. The qualitative
test is more sensitive, 98%–99% specific, and is done by either PCR or by
transcription-mediated amplification
(TMA). The quantitative test can detect
,50 copies of the virus and is done by
either PCR, TMA, or branched chain
DNA (bDNA).
The indirect tests (HCV and genotyping) detect antibodies. The thirdgeneration enzyme assay detects HCV
proteins. It becomes positive eight
weeks after exposure and detects 99%
of immunocompetent individuals. The
recombinant immunoblot assay now has
limited utility thanks to this third
generation test. HCV genotyping detects type-specific antibodies and predicts treatment response.
HEPATITIS UPDATE - Hall
Table 1. Factors Associated with SVR
Viral
Adherence
- Genotype (2 or 3)
- Lower HCV RNA level
- Early virologic response
- More than 80% of intended
treatment for more than 80%
of intended duration
Disease-related
- Absence of advanced fibrosis
- Lack of steatosis
- Higher ribavirin dose
Liver function tests (LFTs) start to
rise 6–12 weeks after exposure, with
a range of 20–26 weeks. However, ALT
level correlates poorly with disease
activity and many individuals have
normal levels despite having chronic
HCV.
The National Institutes of Health
(NIH) Consensus Development Conference in 1997 endorsed pretreatment
liver biopsy as the gold standard for
assessing inflammation (grade) and
extent of fibrosis (stage) in anticipation
of instituting antiviral therapy.18 It is
also used to determine the urgency of
treatment and prognosis, and it can rule
out other diseases, such as fatty liver,
alcoholic liver disease, and hemochromatosis. A liver biopsy is not necessarily
needed with genotypes 2 and 3, since
these are associated with an excellent
prognosis. In untreated patients, a repeat
liver biopsy — the only reliable means of
assessing the progression of fibrosis — is
recommended every three to five years.
Several histologic classifications are
used to standardize results and comparisons when assessing results in different
clinical trials. The three common scoring systems are Knodell, Metavir, and
Ishak systems. The Knodell score, also
known as the histologic activity index,
and the Metavir score have four scores,
from normal to cirrhosis. The Metavir
score was designed to address some of
the shortcomings of the Knodell system;
in addition, it was designed specifically
to stage hepatitis C. The Ishak system
goes from normal (zero) to cirrhosis
(six).
Host factors
-
Lower body weight
Younger age
Women
non African-American
Factors Affecting Prognosis
The factors that affect the progression of fibrosis with a detrimental effect
are external or host related. External
factors are alcohol consumption, drug
use, and cigarette smoking. The hostrelated factors are advanced age at
infection, being African American, male
sex, immunosuppression or co-infection
(HIV, HBV, HAV), and comorbidities
(hemochromatosis, obesity).
Therapy for Hepatitis C
The 2002 NIH consensus conference recommended that all patients
with hepatitis C should be considered
potential candidates for therapy.19 Once
a patient is treated, the optimal endpoint of therapy is sustained virologic
response (SVR). The factors associated
with a SVR are: genotype, absence of
fibrosis, etc (Table 1).
Hepatitis C virus (HCV) RNA
testing is done before therapy, 12 weeks
into therapy, and 24 weeks after the end
of therapy, and its absence is a surrogate
marker for resolution of liver injury,
reduction in fibrosis, and a low likelihood of recurrent HCV infection.
The guidelines for therapy can be
broken down into three areas: those in
whom therapy is widely accepted, those
whose therapy should be individualized,
and those in whom therapy is contraindicated. Indications for therapy are
age .18 years, abnormal LFTs, HCV
RNA level elevation, and acceptable
hematologic and biochemical values
(hemoglobin .13 g/dL, lack of signifEthnicity & Disease, Volume 17, Spring 2007
icant thrombocytopenia, creatinine
,1.5 mg/gL, and liver biopsy without
significant fibrosis).
Therapy needs to be individualized
in those with normal LFTS, continuous
alcohol or drug use, prior treatment
failures with the older regimens, age
,18 years, minimal liver involvement,
decompensated cirrhosis, and HIV coinfection. Absolute contraindications to
therapy are pregnancy, major uncontrolled psychiatric disorders, autoimmune disorders, hemoglobinopathies,
transplant recipients, severe co-morbid
conditions (coronary artery disease,
cerebrovascular accident, end-stage renal
disease, and chronic obstructive pulmonary disease) and hypersensitivity to the
components of therapy.
The use of PEG rather than standard interferon with ribavirin increases
SVR to 54%–56% with genotype 1 and
82% with genotype 2 or 3.20,21 Two
different formulations of PEG-interferon are available: interferon alfa-2a is
dosed at 180 ug subcutaneously every
week, and interferon alfa-2b is dosed at
1.5 ug/kg subcutaneously every week.
Either drug plus oral ribavirin 800–
1200 mg (weight-based dosing) once
a day is given for 48 weeks with genotype
1. The NIH consensus conference recommended that with genotypes 2 or 3,
PEG-interferon plus ribavirin 800 mg be
used for 24 weeks.20,21 Regardless of the
regimen, therapy should be discontinued
if HCV RNA has not decreased by .2
logs at 12 weeks.22
Treatment is associated with many
side effects (Table 2), and <20% of
patients experience severe side effects
that result in discontinuation of their
therapy. Before starting therapy, patients should be thoroughly educated
about the side effects and self-management techniques to help them get
through their therapy. Many of the side
effects can be easily managed with
proper dose reductions, growth factors,
epoetin for anemia, increased fluids and
exercise, acetaminophen, dosing the
medications at night, diphenhydramine,
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HEPATITIS UPDATE - Hall
HEPATITIS E
Table 2. Side effects of therapy
Interferon
Common
More serious
Influenza-like symptoms
Irritability
Diarrhea, gastrointestinal intolerance
Alopecia
Leukopenia, thrombocytopenia
Retinopathy
Thyroid dysfunction
Neuropsychiatric disturbances
serotonin reuptake inhibitors for depression, and thyroid medications.
Milk thistle has been advocated by
some to be beneficial in the treatment of
HCV. It lowers LFTs but does not
affect the virus itself. Viramidine, a ribavirin prodrug, produces less hemolysis, lasts longer in the liver, is less
concentrated in peripheral blood, and
has fewer overall side effects but is not
FDA approved. The protease inhibitor
VX-950 has shown promise in early
clinical trials.
Hepatocellular Carcinoma
Patients with hepatitis B, hemochromatosis, environmental toxins and cirrhosis due to any cause are at increased
risk for developing hepatocellular carcinoma (HCC). Hepatitis C in many
parts of the world is the number one
cause though. Screening for HCC
should include: upper endoscopy in
those with cirrhosis, ultrasound and
serum alfa fetoprotein every six months.
Vaccines
Individuals with chronic liver disease
should receive vaccines for hepatitis A
and B, pneumococcus, and influenza.
HEPATITIS D
Hepatitis D virus, also known as
delta virus, is a defective RNA virus that
can replicate on its own, but it requires
concurrent HBV for assembly and
secretion; as a result, patients with
HDV are always dually infected with
HBV.23 There are three genotypes; all
S2-44
Ribavirin
Cough, shortness of breath
Insomnia
Rash, pruritis
Elevated uric acid
Hemolytic anemia
Teratogenicity
Induction autoimmune diseases
are spread percutaneously, through injection drug use, and through unprotected intercourse. The virus is endemic
in the Mediterranean region and Asia.
Hepatitis D virus (HDV) presents as
either a co-infection—like an acute
hepatitis B infection with its manifestations—or as a super infection—a severe,
acute infection in a previously stable
chronic hepatitis B patient.
Diagnosis
Since HDV is dependent on HBV,
HBsAg is a requirement for the diagnosis of HDV infection. In addition,
antibodies to HDV (IgM and IgG) are
required for the diagnosis. Serum assays
for HDAg are short-lived and are not
clinically available in the United States.
HDV RNA can be detected by molecular hybridization or by PCR.
Treatment
The primary aim and endpoint of
treatment are undetectable HDV RNA
levels, normalization of LFTs, and a decrease of inflammation on liver biopsy.
A secondary aim is suppression of HBV
DNA levels and seroconversion of
HBsAg to HBsAb. Interferon alfa is
the only FDA-approved drug against
HDV. Ribavirin, lamivudine, and other
drugs are ineffective against HDV infection.
Prevention
Hepatitis B affects .350 million
people worldwide. Thus, the only way
to prevent HDV is through primary
education about its risk factors or
through vaccination against HBV.
Ethnicity & Disease, Volume 17, Spring 2007
Epidemiology
The hepatitis E virus (HEV) is an
RNA virus with four genotypes that was
first described in India in 1955. It is
a self-limiting, enterically transmitted
disease like hepatitis A but is more
severe, easily transmitted, and distributed worldwide. Its highest incidence is in
developing countries, and it is the
second most common cause of sporadic
hepatitis in northern Africa and the
Middle East. It is usually spread by
fecally contaminated water, but it can
also be spread by blood and blood
products. There is a low incidence of
person-to-person transmission.
Manifestations
Hepatitis E virus (HEV) infection
has an incubation period of 15–60 days.
It presents like other acute hepatitis
illnesses but with prolonged cholestatis.
There is a low rate of fulminant hepatic
failure, except in pregnant women, who
have a mortality of 15%–25%. The
acute state usually lasts for up to six
weeks, and for those that recover there is
no chronic state.
Diagnosis, Treatment,
and Prevention
Hepatitis E virus (HEV) infection is
diagnosed by detecting HEV in the
serum or feces by PCR or by detecting
IgM antibodies. A March 1, 2007
NEJM article featured a new recombinant HEV vaccine that showed promise
in a phase two trial from Nepal.
Heretofore, treatment is generally supportive since there is no FDA approved
vaccine. Therefore, prevention entails
avoiding contaminated water and uncooked foods in endemic areas.
HEPATITIS G
Epidemiology
The hepatitis G virus (HGV) is
a blood-borne virus that is spread by
HEPATITIS UPDATE - Hall
contaminated blood and blood products. It has a worldwide distribution and
is especially common in blood donors in
the United States. Because this virus
may not produce disease in humans,
blood is not routinely screened for
HGV.
Studies have found that in the
United States, 10%–20% of HGV
patients are also co-infected with
HCV. Mounting evidence has also
shown a protective role of HGV in
HIV patients.24,25
CONCLUSION
The viral hepatic disorders are divided into the acute disorders (hepatitis
A, E, G) and those with acute and
chronic states (hepatitis B, C, D). They
are spread by the fecal-oral route,
perinatally, percutaneously, through
blood or blood products, or by unprotected intercourse. Treatment is
mostly supportive, although several
medications are available, depending
on the individual disorder. Prevention
is through proper sanitary conditions,
vaccination, and education on risk
factors.
ACKNOWLEDGMENTS
I thank Mrs. Westina Fernandes for her
administrative support and critical revision
of this manuscript.
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AUTHOR CONTRIBUTIONS
Design concept of study: Hall
Manuscript draft: Hall
Administrative, technical, or material assistance: Hall
Supervision: Hall
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